Anion photoelectron spectroscopy of small clusters

Anion photoelectron spectroscopy has been carried out on small isolated clusters in the gas phase. The III-V semiconductor duster Ga2N -, and the carbon monohydride clusters C3H- and C5H- were studied. Spectra of Ga2N - were measured at photodetachment wavelengths of 416 nm, 355 nm, and 266 nm using field-free time-of-flight and velocity-map imaging methods. Transitions from the ground state of Ga2N to several states of the neutral were observed and analyzed with the aid of electronic structure calculations and Franck-Condon simulations. For C3H-, transitions originating from a linear/bent (l-C3H) and a cyclic (c-C3H) anionic isomer to the corresponding neutral ground states and low-lying excited states were observed and assigned with the aid of electronic structure calculations and Franck-Condon simulations. Vibrational assignments were made for c-C 3H, while l-C3H was more complicated owing to a large amplitude bending motion and a strong Renner-Teller coupling. Analogous to C3H-, photodetachment transitions of from multiple, energetically close-lying isomers of C5H- were observed and assigned.